Class MatchException

java.lang.Object

java.lang.Throwable

java.lang.Exception

java.lang.RuntimeException

java.lang.MatchException

All Implemented Interfaces:

Serializable

public final class MatchException
extends RuntimeException

Thrown to indicate an unexpected failure in pattern matching.

MatchException may be thrown when an exhaustive pattern matching language construct (such as a switch expression) encounters a value that does not match any of the specified patterns at run time, even though the construct has been deemed exhaustive. This is intentional and can arise from a number of cases:

• Separate compilation anomalies, where parts of the type hierarchy that the patterns reference have been changed, but the pattern matching construct has not been recompiled. For example, if a sealed interface has a different set of permitted subtypes at run time than it had at compile time, or if an enum class has a different set of enum constants at runtime than it had at compile time, or if the type hierarchy has been changed in some incompatible way between compile time and run time.
• null values and nested patterns involving sealed classes. If, for example, an interface I is sealed with two permitted subclasses A and B, and a record class R has a single component of type I, then the two record patterns R(A a) and R(B b) together are considered to be exhaustive for the type R, but neither of these patterns will match against the result of new R(null).
• null values and nested record patterns. Given a record class S with a single component of type T, where T is another record class with a single component of type String, then the nested record pattern R(S(var s)) is considered exhaustive for the type R but it does not match against the result of new R(null) (whereas it does match against the result of new R(new S(null)) does).

MatchException may also be thrown by the process of pattern matching a value against a pattern. For example, pattern matching involving a record pattern may require accessor methods to be implicitly invoked in order to extract the component values. If any of these accessor methods throws an exception, pattern matching completes abruptly and throws MatchException. The original exception will be set as a cause of the MatchException. No suppressed exceptions will be recorded.

See Java Language Specification:

14.11.3 Execution of a switch Statement
14.30.2 Pattern Matching
15.28.2 Run-Time Evaluation of switch Expressions

Since:

21

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
MatchException(String message, Throwable cause)	Constructs an MatchException with the specified detail message and cause.

Method Summary

Methods declared in class Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Modifier and Type	Method	Description
final void	addSuppressed(Throwable exception)	Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.
Throwable	fillInStackTrace()	Fills in the execution stack trace.
Throwable	getCause()	Returns the cause of this throwable or null if the cause is nonexistent or unknown.
String	getLocalizedMessage()	Creates a localized description of this throwable.
String	getMessage()	Returns the detail message string of this throwable.
StackTraceElement[]	getStackTrace()	Provides programmatic access to the stack trace information printed by Throwable.printStackTrace().
final Throwable[]	getSuppressed()	Returns an array containing all of the exceptions that were suppressed, typically by the try-with-resources statement, in order to deliver this exception.
Throwable	initCause(Throwable cause)	Initializes the cause of this throwable to the specified value.
void	printStackTrace()	Prints this throwable and its backtrace to the standard error stream.
void	printStackTrace(PrintStream s)	Prints this throwable and its backtrace to the specified print stream.
void	printStackTrace(PrintWriter s)	Prints this throwable and its backtrace to the specified print writer.
void	setStackTrace(StackTraceElement[] stackTrace)	Sets the stack trace elements that will be returned by Throwable.getStackTrace() and printed by Throwable.printStackTrace() and related methods.
String	toString()	Returns a short description of this throwable.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

MatchException

public MatchException(String message,
 Throwable cause)

Constructs an MatchException with the specified detail message and cause.

Parameters:

message - the detail message (which is saved for later retrieval by the Throwable.getMessage() method).

cause - the cause (which is saved for later retrieval by the Throwable.getCause() method). (A null value is permitted, and indicates that the cause is nonexistent or unknown.)